Definition of Urea breath test (UBT)

Urea breath test (UBT): The urea breath test (UBT) is a procedure for diagnosing the presence of a
bacterium, Helicobacter pylori (H. pylori) that causes inflammation, ulcers,
and atrophy of the stomach. The test also may be used to demonstrate that
H. pylori has been eliminated by treatment with antibiotics.

The urea breath test is based on the ability of H. pylori to break down
urea, a chemical made of nitrogen and carbon, that normally is produced by the
body from excess ("waste") nitrogen and then eliminated in the urine. For
the test, patients swallow a capsule containing urea made from an isotope
of carbon. (Isotopes of carbon occur in minuscule amounts in nature, and can
be measured with special testing machines.) If H. pylori is present in the
stomach, the urea is broken up into nitrogen and carbon (as carbon dioxide).
The carbon dioxide is absorbed across the lining of the stomach and into the
blood. It then is excreted from the lungs in the breath. Samples of
exhaled breath are collected, and the isotopic carbon in the exhaled carbon
dioxide is measured.

If the isotope is detected in the breath, it means that H.
pylori is present in the stomach. If the isotope is not found, H. pylori
is not present. When the H. pylori is effectively treated (eradicated) by
antibiotics, the test changes from positive (isotope present) to negative
(isotope absent).